Light-receiving device and lidar

ABSTRACT

Provided are a light-receiving device and lidar comprising the light-receiving device. The light-receiving device comprises: a first lens comprising a first lens surface for receiving light from an outside and a second lens surface for changing the path of the light received by the first lens surface and outputting the light to the outside; and a sensor on which light transmitted through the second lens surface is incident, wherein the first lens surface is a spherical surface, the second lens surface is an aspherical surface, and the focus of the first lens deviates from the sensor surface of the sensor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Phase of PCT International ApplicationNo. PCT/KR2017/008002, filed on Jul. 25, 2017, which claims priorityunder 35 U.S.C. 119(a) to Patent Application No. 10-2016-0094259, filedin the Republic of Korea on Jul. 25, 2016, and to Patent Application No.10-2016-0100209, filed in the Republic of Korea on Aug. 5, 2016, all ofwhich are hereby expressly incorporated by reference into the presentapplication.

TECHNICAL FIELD

The present invention relates to a high efficient light-receiving deviceconfigured to increase efficiency of light incident at an angle of wideangle, relates to a light-receiving device configured to effectivelyincrease a dynamic range, and relates to a lidar comprising the same.

BACKGROUND ART

Recently, fields of intelligent vehicle and smart cars require proactivevehicular response functions in order to cope with unexpectedcircumstances. That is, there is a need to beforehand ascertaincircumstances that menace safety of drivers and pedestrians such asrecognition of sudden emergence of pedestrians, advance detection ofobstacles at a place deviated from illumination during dark night,detection of obstacles under deteriorated illumination of headlight whenit rains, or detection of road destruction.

To meet these requirements, a scanner is used which is installed on awindshield or a front side of a vehicle to ascertain an object based onemitted light source and to warn a driver in advance, to transmit animage, which is a base for the vehicle to stop by itself or to avoid theobject, to an ECU (Electronic Control Unit) and to obtain the image.

The conventional scanner has used a RaDAR (Radio Detection and Ranging)device. The RaDAR is a radio detection system that uses radio waves(ultrahigh frequency of 10 cm to 100 cm waves) to determine the range,direction, altitude, or velocity of objects by receiving theelectromagnetic waves reflected from the objects, and is used forvehicular scanner. However, there are drawbacks because the RaDAR isexpensive and therefore is not easy to be used for various types ofvehicles.

In order to solve the aforesaid drawbacks, scanners using LiDAR (LightDetection and Ranging) have been developed. The LiDAR, a surveyingmethod that measures distance to a target or an atmospheric phenomenonby illuminating a target with pulsed laser light and measuring thereflected pulses with a sensor using reflectors or scatterers, is alsocalled a laser Lidar. Measurement of time of reflected light iscalculated by clock pulses, and 5-m resolution with a bandwidth of 30MHz and 1-m resolution with a bandwidth of 150 MHz.

A sensor in the Lidar must stably receive a signal of variousdirections, i.e., a signal incident from wide angles. To be morespecific, a vehicular Lidar requires an increased efficiency of lightincident at a wide angle (corresponding to a range of about +70 degreesto −70 degrees to X axis and a range of about +3.4 degrees to −3.4degrees to Y axis) at all angles comprised in relevant ranges.

In order for the typical vehicular Lidar to receive signals of alllights incident at the said wide angle above a predetermined level, acoaxial method has been used that moves along a light receiving part anda light-emitting part through a motor.

However, this motor method suffers drawbacks in that manufacturing costis increased due to synchronization of a light-receiving part and alight-emitting part, addition of a motor, and overall size of modules isalso increased as well. Moreover, when a same cover lens is used for thelight-receiving part and the light-emitting part, another drawback isthat it is difficult to obtain an enhanced performance of lightreceiving part due to scattering. Furthermore, a Lidar module typicallyuses a high-sensitivity APD (Avalanche Photo Diode) for increasedmeasurement distance. However, when the APD is used, it may beadvantageous in terms of measurement of small amount of lights, but mayencounter a “dead zone” having a physical limitation that fails torespond to a large amount of lights.

Thus, the problem of dead zone boils down to a problem of dynamic rangeof a detector disposed on a Lidar module, resulting in disruption ofaccurate measurement of Lidar.

DISCLOSURE Technical Problem

An object of first exemplary embodiment is to provide a high efficientlight receiving lens configured to increase an efficiency of lightincident at an angle of wide angles to above a predetermined level.

Another object of first exemplary embodiment is to provide a highefficient light receiving lens configured to maintain a light efficiencyto above a predetermined level even if an incident angle is increased,by allowing light having passed through a lens of defocusing method tohave a predetermined area on a sensor surface.

Still another object of first exemplary embodiment is to provide a highefficient light receiving lens adequate to a sensor responding to aquantity of light above a predetermined level by disposing a defocusinglens that is not great in changed rate of quantity of transmitting lighteven if an incident angle of light is changed.

An object of second exemplary embodiment is to provide a light-receivingdevice configured to increase a dynamic range capable of increasing thedynamic range by changing a gain of a light receiving element.

Another object of second exemplary embodiment is to provide alight-receiving device configured to increase a dynamic range providedto a light receiving element by allowing a bias voltage changing a gainof a light receiving element to be synchronized with a light output of alight emitting element.

Still another object of second exemplary embodiment is to provide alight-receiving device configured to increase a dynamic range solving adead zone problem that is unresponsive to a relatively large quantity oflight when an APD is used.

Technical Solution

In order to solve the aforesaid technical problems, a light receivinglens module according to a first exemplary embodiment may comprise:

a light receiving lens formed with a first lens surface for receivinglight from an outside, and a second lens surface for changing a path ofthe light received by the first lens surface and outputting the light tothe outside, wherein

at least one or more line segments formed by allowing cross-sectionscomprising an optic axis of the light receiving lens and the second lenssurface to be met may have a predetermined curvature, and at least oneline segment formed by allowing cross-sections comprising an optic axisof the light receiving lens and the second lens surface to be met may bea line segment that changes in curvature.

In the first exemplary embodiment, at least one or more line segmentsformed by allowing the cross-sections comprising an optic axis of thelight receiving lens and the first lens surface to be met may have apredetermined curvature.

In the first exemplary embodiment, the light receiving lens module mayfurther comprise a sensor for detecting light sequentially passingthrough the first lens surface and the second lens surface by beingincident on the light receiving lens from an outside, wherein the lighthaving reached the light receiving lens may be defocused to allow beingreached in a shape having a predetermined area on a sensing area of thesensor.

In the first exemplary embodiment, the predetermined area may be changedin response to at least one or more of incident angle of X axis relativeto the first lens surface and an incident angle of Y axis relative tothe first lens surface.

In the first exemplary embodiment, the incident angle of X axis maycomprise a range of maximum +70˜−70°.

In the first exemplary embodiment, the incident angle of Y axis maycomprise a range of maximum +4˜−4°.

In the first exemplary embodiment, the light having sequentially passedthrough the first lens surface and the second lens surface may reach aposition distancing from a center of the sensor as at least one or moreof incident angles in the incident angle of X axis relative to the firstlens surface, and the incident angle of Y axis relative to the firstlens surface increase through the defocusing.

In the first exemplary embodiment, the sensor may be disposed on theoptic axis.

In the first exemplary embodiment, the light receiving lens may have apositive (+) refractive index.

In the first exemplary embodiment, the light receiving lens module mayfurther comprise: a separate lens or a separate structure interposedbetween the sensor and the second lens surface to increase an efficiencyof light incident on the sensor.

In the first exemplary embodiment, the light receiving lens module mayfurther comprise: at least one or more connection parts formed on asurface connecting the first lens surface and the second lens surface tophysically connect the light receiving lens and the light receivingpart.

In the first exemplary embodiment, at least each one or more of theconnection parts may comprise at least one or more protrusions.

In order to solve the aforesaid problems, a light receiving lenscomprising a first lens surface and a second lens surface for allowinglight incident from an outside to reach a sensor according to anotherfirst exemplary embodiment may be such that a curvature of a linesegment formed by allowing a first virtual plane to meet the first lenssurface may be constant, a curvature of a line segment formed byallowing a second virtual plane to meet the first lens surface may beconstant, a curvature of a line segment formed by allowing a firstvirtual plane to meet the second lens surface may be constant, and acurvature of a line segment formed by allowing a second virtual plane tomeet the second lens surface may not be constant, when an optic axisextended to a height direction of the light receiving lens is defined asa Z axis, an axis perpendicular to the Z axis to form an intersectionpoint by passing through one point on the Z axis and extended to alengthwise direction of the lens is defined as an X axis, an axisperpendicular to the X axis and the Z axis to penetrate an intersectionpoint of the X axis and the Z axis and to be extended to a widthwisedirection of the lens is defined as a Y axis, a virtual plane comprisingthe X axis and the Z axis is defined as a first virtual plane, and avirtual plane comprising the Y axis and the Z axis is defined as asecond virtual plane.

In order to solve the aforesaid problems, an optical device according toa second exemplary embodiment of the present invention may comprise:

a light receiving element for detecting light reflected and transmittedfrom a subject;

a voltage part providing a first bias voltage or a second bias voltageto the light receiving element; and

a controller for controlling the voltage part so that the second biasvoltage provided from the voltage part is synchronized with a lightoutput of a light emitting part to be provided to the light receivingelement.

In the second exemplary embodiment, the second bias voltage may comprisea voltage in which a sub bias voltage is added to the first biasvoltage.

In the second exemplary embodiment, the sub bias voltage may becomprised in a range of +50V˜−50V.

In the second exemplary embodiment, the sub bias voltage may comprise anAC-shaped or pulse-shaped voltage that changes to a time.

In the second exemplary embodiment, the controller may be such that thelight emitting part and the voltage part may be simultaneously inputtedwith a seed signal, and the voltage part may output the second biasvoltage based on a time when the seed signal is inputted.

In order to solve the aforesaid problems, a Lidar module according toanother second exemplary embodiment may comprise:

a light receiving element for detecting light reflected and transmittedfrom a subject;

a first voltage part for providing a bias voltage to the light receivingelement;

a second voltage part for providing a sub bias voltage to the lightreceiving element; and

a controller for controlling the second voltage part so that the subbias voltage is synchronized with a light output of a light emittingpart to be provided to the light receiving element.

In order to solve the aforesaid problems, a Lidar module according toanother second exemplary embodiment of the present invention maycomprise:

a light receiving element for detecting light reflected and transmittedfrom a subject;

a first voltage part for providing a bias voltage to the light receivingelement;

a second voltage part for providing a sub bias voltage to the lightreceiving element; and

an MPD (Monitoring Photo Diode) for controlling the second voltage partso that a light output outputted from a light emitting part to besynchronized with the light output detected with the sub bias voltageand to be provided to the light receiving element.

In the second exemplary embodiment, the sub bias voltage may becomprised in a range of maximum +50V˜−50V.

In the second exemplary embodiment, the sub bias voltage may comprise anAC-shaped or pulse-shaped voltage that changes to a time.

In the second exemplary embodiment, the controller may be such that thelight emitting part and the second voltage part may be simultaneouslyinputted with a seed signal, and the second voltage part may output thesub bias voltage based on a time when the seed signal is inputted.

In the second exemplary embodiment, the monitoring photo diode may inputa seed signal to the second voltage part in response to the detectedlight output, and the second voltage part may output the sub biasvoltage based on a time when the seed signal is inputted.

Advantageous Effects

According to at least one of the first exemplary embodiments, efficiencyof light incident at an angle of wide angle can be increased to apredetermined level.

Furthermore, according to at least one of the first exemplaryembodiments, a light efficiency can be maintained to above apredetermined level even if an incident angle is increased, by allowinglight having passed through a lens of defocusing method to have apredetermined area on a sensor surface.

Furthermore, according to at least one of the first exemplaryembodiments, a sensor responding to a quantity of light above apredetermined level may be adequate by disposing a defocusing lens thatis not great in changed rate of quantity of transmitting light even ifan incident angle of light is changed.

Furthermore, according to at least one of the second exemplaryembodiments, a dynamic range can be increased by changing a gain of alight receiving element.

Furthermore, according to at least one of the second exemplaryembodiments, a bias voltage changing a gain of a light receiving elementmay be synchronized with a light output of a light emitting element andmay be provided to a light receiving element.

Furthermore, according to at least one of the second exemplaryembodiments, a dead zone problem that is not responding to a relativelylarge quantity of light can be solved when an APD is used.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating an example of receiving a lightincident on with a wide angle corresponding to a range of about+70°˜−70° to an X axis, and a range of about +3.4°˜−3.4° to a Y axis ina vehicular Lidar.

FIG. 2 is a schematic view illustrating a first cross-section of a firstlens according to a first exemplary embodiment of present invention.

FIG. 3 is a schematic view illustrating a second cross-section of afirst lens according to a first exemplary embodiment of presentinvention.

FIG. 4 illustrates an example of incident angle being distanced from acenter of a sensor surface, as an incident angle of a light incident ona first lens is increased according to a first exemplary embodiment ofpresent invention.

FIG. 5 is a schematic view illustrating an example of an area disposedon a sensor surface being distanced from a center of the sensor surfacewhen a first lens is defocused according to a first exemplary embodimentof present invention.

FIG. 6 is a schematic view when a second lens or a mechanism is addedbetween a first lens and an image sensor according to a first exemplaryembodiment of present invention.

FIGS. 7 to 10 are schematic views illustrating an example where a firstlens according to a first exemplary embodiment of present invention isactually embodied.

FIG. 11 is a schematic view illustrating an example where an ADP is usedas a light receiving element in a conventional Lidar module.

FIG. 12 is a schematic view illustrating an example where a gain ischanged in response to changes in temperature of a conventional Lidarmodule of FIG. 11 or to a bias voltage.

FIG. 13 is a schematic view illustrating an example where a gain of anAPD is increased in response to changes in bias voltage when atemperature is constant in a light-receiving device for increasing adynamic range according to a second exemplary embodiment of presentinvention.

FIG. 14 is a schematic view illustrating an optical device according toa second exemplary embodiment of present invention.

FIGS. 15 to 17 are schematic views illustrating a sub bias voltageapplied to a light receiving element in the optical device of FIG. 14and a second bias voltage thereof.

FIG. 18 is a schematic view illustrating a Lidar module according to athird exemplary embodiment of present invention.

FIG. 19 is a schematic view illustrating a Lidar module according to afourth exemplary embodiment of present invention.

BEST MODE

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings, wheresame or like elements will be provided with same reference numeralsregardless of drawing signs and redundant explanation thereto will beomitted. As used herein, the suffixes ‘module’, and ‘part’ may be usedfor elements in order to facilitate the disclosure. Significant meaningsor roles may not be given to the suffixes themselves and it isunderstood that the ‘module’, and ‘part’ may be used together orinterchangeably. Furthermore, in describing the present invention,detailed descriptions of constructions or processes in explainingexemplary embodiments that are known in the art may be omitted to avoidobscuring appreciation of the invention with unnecessary detailregarding such known constructions and functions. Still furthermore, theaccompanied drawings used herein are for the purpose of helping an easyappreciation of exemplary embodiments disclosed in the specificationonly and are not intended to be limiting of the general inventiveconcept, and it will be appreciated that various modifications,additions and substitutions comprised in the general inventive conceptare possible, without departing from the scope and spirit of theinvention as disclosed in the accompanying claims.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Asused herein, the terms “a” and “an” are open terms that may be used inconjunction with singular items or with plural items.

The terms “comprises,” “comprising,” “comprising,” and “having,” areinclusive and therefore specify the presence of stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof.

The present invention comprises four exemplary embodiments. The firstexemplary embodiment relates to a light-receiving device using adefocused first lens and a Lidar. The second, the third and fourthexemplary embodiments relate to an optical device and a Lidar configuredto increase a dynamic range by changing a gain of light receivingelement, and to solve a dead zone unresponsive to a relatively largequantity of lights using an APD as a light receiving element.

First, the first exemplary embodiment will be described. Hereinafter, indescribing the first exemplary embodiment, an “optic axis” may mean anoptic axis of first lens (100)”. The “optic axis” may be formed to avertical direction (up/down direction). “a major axis of first lens” anda minor axis of first lens” may be axes orthogonal to an “optic axis” onthe first lens, and may be axes mutually orthogonal to each other on thefirst lens. “a major axis of first lens” and a minor axis of first lens”may be disposed on a plane surface perpendicular to the “optic axis”.Although only one “optic axis” may be existent, the “major axis of firstlens” and a minor axis of first lens” may be existent in a plural numberas long as the abovementioned conditions are satisfied. A length of“major axis of first lens” may be longer than that of the “minor axis offirst lens”. In the Orthogonal Coordinate System shown on the drawings,z axis may be an “axis parallel with the optic axis”, x axis may be oneof the “major axes of first lens”, and y axis may be one of the “minoraxes of first lens”.

FIG. 1 is a schematic view illustrating an example of receiving a lightincident on with a wide angle corresponding to a range of about+70°˜−70° to an X axis, and a range of about +3.4°˜−3.4° to a Y axis ina vehicular Lidar.

As described above, in the fields of intelligent vehicle and smart cars,signals of various directions must be received from, for example, adistance recognition sensor and/or a motion recognition sensor, that is,signals of wide angle must be received in order to proactively respondto unexpected circumstances.

As illustrated in FIG. 1, a light receiving part (110) disposed on aLidar mounted on a vehicle must receive light incident on from a wideangle corresponding to a range (120) of about +70°˜−70° to an X axis,and a range (130) of about +3.4°˜−3.4° to a Y axis at all anglescomprising relevant ranges on a relatively constant base.

Hereinafter, exemplary embodiments of present invention will bedescribed in detail with reference to the accompanying drawings. Itshould be readily apparent to those of skill in the art that theinvention may be embodied in other particular modifications within thespirit and scope of the invention.

However, the first lens (200) described through FIGS. 2 to 6 simplyillustrate only essential elements in introducing characteristicfunctions of the present invention, and therefore it should be readilyapparent to those of skill in the art that other various elements may becomprised in the invention. The first lens (200) may be called a “highefficient light receiving lens”.

FIG. 2 is a schematic view illustrating a first cross-section of a firstlens (200) according to a first exemplary embodiment of presentinvention. Here, the first cross-section may be a cross-section to amajor axis direction of first lens (200). Thus, the first cross-sectionmay be in plural number. The first cross-section illustrated in FIG. 2among the plurality of first cross-sections may be a first cross-sectioncomprising all the x axis and y axis.

Referring to FIG. 2, the first lens (200) may comprise a first lenssurface (201) and a second lens surface (202). As illustrated in FIG. 2,the first lens surface (201) on the first cross-section may be formedwith a convex shape to a light source (or subject) direction, and thesecond lens surface (202) may be formed with a concave shape to a sensor(240) direction or with a convex shape to a light source (or subject)direction.

The first lens surface (201) on the first cross-section may have aspherical shape. Now, the spherical shape of first lens surface (201)will be described in more detail. At least one line segment in the linesegments formed by allowing the cross-sections comprising an optic axisof first lens (200) and the first lens surface (201) to meet may have apredetermined curvature.

Here, the optic axis may be a path of light that does not generaterefraction, and according to other expressions, the optic axis may meana central axis to a vertical direction of first lens (200). Meantime,the first lens surface (201) on the first cross-section maysubstantially and evenly accept the quantity of light incident at allangles comprising a range of maximum +70°˜−70° to an X axis due to arelevant hemispheric shape of the first lens surface.

The first lens (200) according to the first exemplary embodiment mayhave a positive (+) refractive index.

On the other hand, a sensor (240) may be disposed underneath the secondlens surface (202). To be more specific, it is preferable that thesensor (240) be disposed at a center of hemispheric shape orsemi-circular shape, which is the shape of first lens surface (201) orthe second lens surface (202) on the first cross-section. The center ofhemispheric shape or semi-circular shape may be a center of a sphere ora circle at a time when a complete sphere or circle is formed byextending the given hemisphere or semi-circle. Furthermore, a center ofsensor (240) may be disposed at a center of hemispheric or semi-circularshape. Furthermore, the sensor (240) may be downwardly (z axis directionof FIG. 2) spaced apart from the center of hemispheric or semi-circularshape.

Furthermore, as a detailed exemplary embodiment, a length (210) to an xaxis direction of high efficient light receiving lens (200) according tothe first exemplary embodiment may be 43.8 mm, and a distance to thefirst lens surface (201) from a center of hemispheric shape, which is aradius length (220) of relevant hemispheric shape, may be 21.9 mm whichis half the length of 43.8 mm. Furthermore, the sensor (240) may bedownwardly (−Z axis direction of FIG. 2) spaced apart from a center ofhemispheric shape by about 2 mm to 5 mm.

Meantime, a ratio of length of first lens (200) cut through the firstcross-section, to be more specific, a ratio between a radius length(200) of hemispheric shape and a length (210) to an x axis direction offirst lens (200) may be variably changed within a range satisfying1:21.9. To be more specific, it is preferable that a relevantly cutlength ratio comprise 1:25 to 1:35.

Furthermore, when thickness (reference numeral 230 of FIG. 3) of firstlength (200) according to the first exemplary embodiment, a radiuslength (220) of first lens surface (201), or diameter (210) isincreased, or a total surface area of lens is increased, a totalquantity of light accepted into the lens may be increased, and as aresult, it is preferable that a diameter (D) of sensor detecting anincident light be increased.

FIG. 3 is a schematic view illustrating a second cross-section of afirst lens (200) according to a first exemplary embodiment of presentinvention. Here, the second cross-section may be a cross-section to aminor axis direction of first lens (200). Hence, the secondcross-section may be in plural number. The second cross-sectionillustrated in FIG. 3 in the plurality of second cross-sections may be asecond cross-section comprising all the y axis and z axis.

Referring to FIG. 3, a first lens surface (201) on the secondcross-section may have a spherical shape, and the second lens surfacemay have an aspherical shape.

Now, the aspherical shape of second lens surface (202) will be describedin more detail. At least one line segment in the line segments formed byallowing the cross-sections comprising an optic axis (z axis) of firstlens (200) and the second lens surface (202) to meet may have anon-predetermined curvature.

Meantime, the second lens surface (202) on the second cross-section mayincrease efficiency of light incident at +4° to −4° to a y axisdirection due to relevant aspheric shape.

The first lens (200) according to the first exemplary embodiment may bedeviated in focus from a sensor surface (410) of sensor (240). In thiscase, the first lens (200) may be so disposed as to allow the focus tobe defocused to the sensor surface (410) of sensor (240) and to opticaxis direction (z axis). As a result, light having passed the first lens(200) may arrive on the sensor surface (410) of sensor (240) with ashape having a predetermined area (not spot).

Thickness (230) of first lens surface (201) may be 26.5 mm in thespherical shape of first lens surface (201) on the second cross-sectionof first lens (200) according to the first exemplary embodiment.

Meantime, the predetermined area reached to a sensing region of thesensor (240) by the defocusing may be changed by at least one of anincident angle of x axis to the first lens surface (201) and an incidentangle of y axis to the first lens surface (201).

It is preferable that the incident angle to x axis comprise a range of+70°˜−70°, and an incident angle to y axis comprise a range of +4°˜−4°.Explanation thereto will be continued through the following FIGS. 4 and5.

FIG. 4 illustrates an example of incident angle being distanced from acenter of a sensor surface, as an incident angle of a light incident ona first lens is increased according to a first exemplary embodiment ofpresent invention.

It can be observed from FIG. 4 that an incident angle of y axis to thefirst lens surface (201) among incident angles incident on the firstlens (200) of first exemplary embodiment is distanced from a center ofsensor surface (410) when sequentially increased from 0 degree, 1.7degree and 3.4 degrees.

Thus, if a focus of first lens (200) is so arranged as match to thesensor surface (410) of sensor (240), the focus may be concentrated toone spot to reach the sensor surface (410). Hence, light incident at 3.4degree to y axis direction may not be detected because being incidentoutside of sensor surface (410).

In contrast, the light incident on the sensor surface (410) through thedefocusing of first lens (200) of the aforementioned first exemplaryembodiment can be incident to an area which is not a spot. FIG. 5 is aschematic view illustrating an example of light incident on a highefficient light receiving lens according to the first exemplaryembodiment being defocused and incident on a sensor surface.

Referring to FIG. 5, in the first lens (200) according to a firstexemplary embodiment, when an incident angle to y axis relative to thefirst lens surface (201) is increased to 3.4° compared with 0°, lighthaving passed through the second lens surface (202) may reach a positiondistanced from a center (B) of sensor surface (410), but at least aportion can be sensed and detected because of being incident, not on aspot, but on a surface.

Meantime, it can be ascertained that the predetermined area on whichlight having passed the second lens surface (202) reaches a sensing areaof sensor (240) may be changed depending on at least one of incidentangle of x axis relative to the first lens surface (201) and incidentangle of y axis relative to the first lens surface (201).

For example, when a lens is formed with PMMA (polymethylmethacrylate),and a light source is moved to a range of +70°˜−70° to x axis at adistance spaced apart by 30 m from the sensor (240), and a light sourceis moved to a range of +4˜−4° to y axis, a light corresponding to apower of 1 W can be outputted, and when a diameter of sensing surface(410) of sensor (230) is 2 mm, the quantity of light incident on thesensor (240) may be 3 nW.

At this time, when an incident angle is 0°, a diameter of predeterminedarea of light that has passed the second lens surface (410) disposed atthe sensor surface (410) may be about 2.2 mm, and when an incident angleis 3.4°, a diameter of predetermined area of light having passed thesecond lens surface (202) disposed on the sensor surface (410) may beabout 2.1 mm.

That is, when the diameter of sensor surface (410) of sensor is about 2mm, and when an incident angle is 0°, the light having passed the secondlens surface (202) may reach the sensor surface (410) at an area ratioof about 90%, and when an incident angle is 3.4°, light having passedthe second lens surface (202) may reach the sensor surface (410) at anarea ratio of about 60%.

Various exemplary embodiments of incident angle of x axis relative tothe first lens surface (201) related thereto and incident angle of yaxis relative to the first lens surface (201) may be referred to thefollowing Table 1.

TABLE 1 quantity of incident light on sensor Focusing lens defocusinglens change rate of quantity of light incident angle sensor sensor foreach angle horizontal vertical diameter (2 mm) diameter (2 mm) Focusinglens defocusing lens  0° 0°   9.10E−09 8.87E−09 1.17229E−09 3.00617E−10 0° 3.4° 5.11E−09 7.85E−09 45° 0°   4.32E−09 6.92E−09   8.23E−102.78942E−10 45° 3.4° 1.52E−09 5.97E−09 70° 0°   2.04E−09 3.18E−093.41305E−10 5.62705E−11 70° 3.4° 8.79E−10 2.99E−09

Meantime, various exemplary embodiments are shown as in the followingTable 2 for a case of using a first lens according to the firstexemplary embodiment in the detailed examples and a case of no lens.

TABLE 2 case of no lens case of using a lens incident angle sensor sizesensor size sensor size sensor size horizontal (x) vertical (y) (2 mm)(1 mm) (1.5 mm) (2 mm)  0° 0°   1.44E−09 1.98E−09 4.22E−09 8.87E−09 45°0°   9.61E−10 1.29E−09 3.18E−09 6.92E−09 70° 0°   5.24E−10 8.62E−101.61E−09 3.18E−09  0° 3.4° 1.40E−09 2.52E−09 4.09E−09 7.85E−09 45° 3.4°9.17E−10 2.16E−09 4.09E−09 5.97E−09 70° 3.4° 6.11E−10 9.46E−10 1.25E−093.01E−09

That is, the defocused first lens (200) may be adequate to a sensor(410) that reacts to a predetermined quantity of light whose change ratein quantity of light is not greatly changed as shown in Tables 1 and 2,even if an incident angle of light is changed.

FIG. 6 is a schematic view when a mutually different lens or a mechanismis added between a first lens (200) and an image sensor (410) accordingto a first exemplary embodiment of present invention in order toincrease the efficiency of light incident on the sensor (401).

Referring to FIG. 6, as described before, the sensor (410) may bedisposed at a lower center part of first lens (200). Here, a separatedifferent lens or an optical mechanism (300) may be additionallydisposed between the first lens (200) and the sensor (410) in order toincrease an optical (light) efficiency.

To be more specific, FIG. 6 illustrates an example where a hemisphericshape of second lens (300) is interposed between the first lens (200)and the sensor (240).

In the detailed examples according to the Tables 1 and 2, variousexemplary embodiments are shown in the following Table 3 for a casewhere only the first lens (200) is used and a case where the second lens(300) is additionally used.

TABLE 3 incident quality of light for a sensor when a hemisphereric lenswas added (W) Sensor size 1 mm 1.5 mm 2 mm hemisphere hemispherehemisphere hemisphere hemisphere hemisphere horizontal vertical Ref. 2mm 2.2 mm 2.5 mm 3 mm Ref. 2.2 mm Ref. 2.2 mm  0°   0° 1.98E−09 3.73E−094.03E−09 3.79E−09 4.26E−09 4.22E−09 8.72E−09 8.87E−09 2.09E−08 45°   0°1.29E−09 2.87E−09 2.86E−09 2.65E−09 2.72E−09 3.18E−09 7.35E−09 6.92E−091.30E−08 70°   0° 8.62E−10 1.44E−09 1.46E−09 1.44E−09 1.52E−09 1.61E−093.52E−09 3.18E−09 6.53E−08  0° 3.4° 2.52E−09 4.72E−09 4.59E−09 4.98E−094.60E−09 4.09E−09 8.79E−09 7.85E−09 1.28E−08 45° 3.4° 2.16E−09 3.43E−093.45E−09 2.97E−09 3.53E−09 4.09E−09 4.93E−09 5.97E−09 1.03E−08 70° 3.4°9.46E−10 1.73E−09 1.87E−09 1.46E−09 1.54E−09 1.25E−09 3.35E−09 2.99E−095.57E−09

That is, when a second lens (300) of PMMA material is disposed on thesensor (240), the quantity of light incident on the sensor (240) may beincreased as shown in Table 3. To be more specific, when a radius ofsecond lens (300) is about 2.2 mm, it can be ascertained that theoptical efficiency increases by about two times over an opticalefficiency when the second lens (300) is not available (Ref.).

Meantime, the sensor (240) of FIG. 6 may be also downwardly (−z axisdirection in FIG. 2) spaced apart by about 2 mm˜5 mm from a center ofhemispheric shape as explained in the foregoing.

FIGS. 7 to 10 are schematic views illustrating an example where a firstlens according to a first exemplary embodiment of present invention isactually embodied.

First, as illustrated in FIG. 7, the first cross-section ofaforementioned FIG. 2 can be ascertained in more detail. To be morespecific, the high efficiency light receiving lens of FIG. 7 maycomprise a third plane surface (205) connecting the first lens surface(201) and the second lens surface (202) and a plurality of support legs(209).

Here, the plurality of relevant support legs (209) is an element toallow the first lens according to the present invention to be physicallyconnected to the light receiving part formed with a sensor, and may bedisposed at a position spaced apart by about 5.8 mm on a firstcross-section from a distal end of the first lens surface (201) asillustrated in FIG. 7.

Next, the aforementioned second cross-section of FIG. 3 may be morespecifically ascertained if referred to FIG. 8.

As shown in FIG. 8, the plurality of support legs (209) may be disposedat a position spaced apart by about 5.2 mm on the second cross-sectionfrom a distal end of first lens surface (201). Furthermore, a thicknessof each of the plurality of support legs (209) may be about 4-Ø3 mm, anda length protruded from a third plane surface (205) and a fourth planesurface (206) connecting the first lens surface (201) and the secondlens surface (202) by the plurality of support legs may be about 3.5 mm.

Meantime, a distance spaced apart on the optic axis by the first lenssurface (201) and the second lens surface (202) may be about 14 mm, anda radius length of relevant hemispheric shape, which is a distance froma center of the hemispheric shape to the first lens surface (201), maybe, as discussed above, about 21.9 mm.

Next, the third plane surface (205) and the fourth plane surface (206)connecting the first lens surface (201) and the second lens surface(202) mentioned through FIGS. 7 and 8 among the plurality of surfacesforming the first lens (200) according to the first exemplary embodimentmay be specifically ascertained in detail from FIG. 9.

Meantime, a length to an x axis (X axis of FIG. 2) of first lensaccording to the first exemplary embodiment may be about 43.8 mm asexplained through FIG. 2, and a thickness of first lens surface (201)formed on the first lens (200) may be about 26.5 mm, as elaboratedthrough FIG. 3.

Lastly, a 3D (3 dimensional) shape of first lens according to thepresent invention explained via 2D (2 dimensional) shape through FIGS. 7to 9 may be ascertained from FIG. 10.

To be more specific, it is preferable that actually realized examples offirst lens explained through FIGS. 7 to 10 satisfy the numerical valuesdescribed in the following Tables 4 and 5 and the equation 1, where S1and S2 respectively denote the spherical first lens surface (201) andthe aspherical second lens surface (202).

TABLE 4 Name Rainbow Lens Material PMMA Effective DiameterSurface-S1: >24.8 Surface-S2: >26.5 coating (Surface_S2) Transmissionband (T > 90%): 900~910 nm Blocking range (T < 0.5%): 600~1100 nm AOI oflens top surface: −4′~+4′ AOI of lens bottom surface: −20′~+20′ CoatingDiameter Surface-S1: >24.8 Surface-S2: >26.5 Effective Focal Length18.65 mm Surface S1 & S2 (P-V) Figure (Design R): <50 um Surface Quality(MIL.) MIL 80-60

Here, the coating of the second lens surface (202) may be so configuredas to perform a bandpass function for detecting only the wavelengthpre-set by the first lens (200) according to the first exemplaryembodiment.

TABLE 5 S1 S2 Y Curvature 0.0753843126 −0.0521044905 Y Radius13.2653593961 −19.1922037933 Conic Constant (K) — — A (4th) —0.0001549820 B (6th) — 3.6450096648e−08 C (8th) — —

$\begin{matrix}{z = {\frac{y^{2}}{R\left( {1 + \sqrt{1 - {\left( {1 + K} \right){y^{2}/R^{2}}}}} \right)} + {B\; 4y^{4}} + {B\; 6y^{6}} + {B\; 8y^{8}} + {B\; 10y^{10}} + {B\; 12y^{12}} + {B\; 14y^{14}}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

The Equation 1 denotes a numerical expression for aspheric surface,where R may be −19.1922037933, K may be 0, B4 may be 0.0001549820, B6may be 3.6450096648e-8, and B10, B12 and B14 may be respectively 0.

The first lens (200) according to the first exemplary embodiment of thepresent invention may be explained as under in more detail withreference to FIGS. 7 to 10.

First, an optic axis extended to a height direction of first lens (200)may be defined as z axis (e.g., z axis of FIG. 2), an axis perpendicularto the z axis to pass through one spot on the z axis and to form anintersection and extended to a lengthwise direction of first lens may bedefined as an x axis (e.g., x axis of FIG. 2), an axis perpendicular tox axis and z axis to pass through an intersection between x axis and zaxis and extended to widthwise direction of first lens may be defined asy axis (e.g., y axis of FIG. 2), a virtual plane surface comprising arelevant x axis and z axis may be defined as a first virtual planesurface (e.g., a first cross-section of FIG. 2), and a virtual planesurface comprising a relevant y axis and z axis may be defined as asecond virtual plane surface (e.g., a second cross-section of FIG. 3).

At this time, as illustrated in FIGS. 7 to 10, a curvature of linesegment formed by the first virtual plane surface to meet the first lenssurface of first lens may be constant, and a curvature of line segmentformed by the second virtual plane surface to meet the first lenssurface of first lens may be constant.

Furthermore, a curvature of line segment formed by the first virtualplane surface to meet the second lens surface of first lens may beconstant, and a curvature of line segment formed by the second virtualplane surface to meet the second lens surface of first lens may not beconstant.

Meanwhile, the shape and the number of plurality of support legs (209)illustrated in FIGS. 7 to 10 are a detailed exemplary embodiment thatconnects the first lens and the light receiving part, and it should benoted that other types of shapes or other number of support legscomprised in the first lens are not excluded.

In all, the first lens according to the first exemplary embodiment mayincrease efficiency of light incident on at all angles of optical anglesusing only a lens to a predetermined level, without a mechanical elementsuch as a motor, and light that has passed through a lens via a lens ofdefocusing method is allowed to have a predetermined area on a sensorsurface, such that even if an incident angle is increased, theefficiency of light can be maintained to above a predetermined level,whereby the first lens may be adequate to a sensor reacting to aquantity of light above a predetermined level.

Hereinafter, structure of first lens according to the first exemplaryembodiment will be described in detail with reference to FIGS. 1 to 10.

The first lens (200) according to the first exemplary embodiment maycomprise a first lens surface (201) for receiving light from outside,and a second lens surface (202) for changing a path of the lightreceived by the first lens surface (201) and outputting the light to theoutside. In addition, the first lens (200) may further comprise a firstplane surface (203), a second plane surface (204), a third plane surface(205), a fourth plane surface (206) and a fifth plane surface.

The first lens surface (201) and the second lens surface (202) may berespectively an optical surface through which light passes. The firstplane surface (203), the second plane surface (204) and the fifth planesurface may be respectively a plane surface generated while the firstlens (200) is manufactured. The third plane surface (205) and the fourthplane surface (206) may be respectively a connection surface forconnecting the first lens surface (201) and the second lens surface(202).

The sensor (240) may be incident on by light having passed the secondlens surface (202). Furthermore, a focus of first lens (200) may becharacterized by being deviated (defocused) from the sensor surface(241) of the sensor (240). It is preferable that the focus of the firstlens (200) be deviated from the sensor surface (241) of the sensor (240)to an optic axis direction. That is, a distance from a principal pointof the first lens (200) to the sensor surface (241) of the sensor (240)may be longer or shorter than a focal distance.

The first lens surface (201) may comprise a first spherical surface(201-1). The first lens surface (201) may take a hemispheric shape,whereas the second lens surface (202) may comprise a first asphericalsurface (202-1), a second aspherical surface (202-2) and a thirdaspherical surface (202-3). The second lens surface (202) may be anaspherical surface.

The first aspherical surface (202-1) may be disposed at a distal end ofone side to a minor axis direction (y axis) of first lens (200), thethird aspherical surface (202-3) may be disposed at a distal end ofother side to a minor axis direction (y axis) of first lens (200), andthe second aspherical surface (202-2) may be disposed between the firstaspherical surface (202-1) and the third aspherical surface (202-3).

Referring to FIG. 3, between the first aspherical surface (202-1) andthe second aspherical surface (202-2), there may be existent aninflection point at a cross-section to a minor axis direction (y axis)of first lens (200), and between the third aspherical surface (202-3)and the second aspherical surface (202-2), there may be existent aninflection point at a cross-section to a minor axis direction (y axis)of the first lens (200).

Referring now to FIGS. 2 and 3, the first spherical surface (201-1), thefirst aspherical surface (202-1), the second aspherical surface (202-2)and the third aspherical surface (202-3) may be formed with a convexcurvature to a direction opposite to a direction disposed with thesensor (240) on a cross-section to a major axis direction (x axis) offirst lens (200), and the second aspherical surface (202-2) may beformed with a convex curvature to a direction disposed with the sensor(240) on a cross-section to a minor axis direction (y axis) of firstlens (200).

The first spherical surface (201-1) may have a positive (+) refractivepower on a cross-section to a major axis direction (x axis) of firstlens (200). The first aspherical surface (202-1), the second asphericalsurface (202-2) and the third aspherical surface (202-3) may have anegative (−) refractive power on a cross-section to a major axisdirection (x axis) of the first lens (200).

The first spherical surface (201-1) and the second aspherical surface(202-2) may have a positive (+) refractive power on a cross-section to aminor axis direction (y axis) of the first lens (200). The firstaspherical surface (202-1) and the third aspherical surface (202-3) mayhave a negative (−) refractive power on a cross-section to a minor axisdirection (y axis) of the first lens (200). The second asphericalsurface (202-2) may have a positive (+) refractive power on across-section to a minor axis direction (y axis) of first lens (200).

Now, referring to FIGS. 9 and 10, the first lens (200) may comprise afirst plane surface (203) disposed between a distal end of one side to aminor axis direction (y axis) of first lens (200) on the first sphericalsurface (201-1) and a distal end of one side to a minor axis direction(y axis) of first lens (200) on the first aspherical surface (202-1).

Furthermore, the first lens (200) may comprise a second plane surface(204) disposed between a distal end of the other side to a minor axisdirection (y axis) of first lens (200) on the first spherical surface(201-1) and a distal end of the other side to a minor axis direction (yaxis) of first lens (200) on the third aspherical surface (202-1).

The first plane surface (203) and the second plane surface (204) may beperpendicular to a minor axis (y axis) of first lens (200). The firstplane surface (203) and the second plane surface (204) may be a surfacegenerated when the first lens (200) is manufactured by molding. A jig, asliding mold or a fixing mold is arranged in order to fix the first lens(200) in the molding process and after the molding, the first lens (200)may be generated with a first plane surface (203) and the second planesurface (204).

Referring to FIGS. 9 and 10, the first lens (200) may comprise a thirdplane surface (205) disposed between a distal end of one side to a majoraxis direction (x axis) of first lens (200) on the first sphericalsurface (201-1) and a distal end of one side to a major axis direction(x axis) of first lens (200) on the first aspherical surface (202-1),the second aspherical surface (202-2) and the third aspherical surface(202-3).

Furthermore, the first lens (200) may comprise a fourth plane surface(206) disposed between a distal end of the other side to a major axisdirection (x axis) of first lens (200) on the first spherical surface(201-1) and a distal end of the other side to a major axis direction (xaxis) of first lens (200) on the first aspherical surface (202-1), thesecond aspherical surface (202-1) and a third aspherical surface(202-3).

The third plane surface (205) and the fourth plane surface (206) may beperpendicular to a major axis of the first lens (200). The third planesurface (205) and the fourth plane surface (206) may be a surface forconnecting the first lens surface (201) and the second lens surface(202) and for supporting the first lens (200). To this end, the thirdplane surface (205) and the fourth plane surface (206) may be disposedwith a plurality of support legs (209).

The first lens (200) may further comprise a fifth plane surface (notshown) disposed between the first spherical surface (201-1) and thethird plane surface (205), and a sixth plane surface (not shown)disposed between the first spherical surface (201-1) and the fourthplane surface (206). The fifth plane surface (not shown) and the sixthplane surface (not shown) may be disposed to be symmetrical about anoptic axis. The fifth plane surface (not shown) and the sixth planesurface (not shown) may be parallel with an optic axis. The fifth planesurface (not shown) and the sixth plane surface (not shown) may berespectively a cut surface generated when a plurality of first lenses(200) is cut during manufacturing of the plurality of first lens (200)using a molding.

In more detailed explanation using FIGS. 9 and 10, the first lens (200)may further comprise a plurality of support legs (209).

The plurality of support legs (209) may comprise a first support leg(209-1) disposed on the third plane surface (205), a second support leg(209-2) disposed on the third plane surface (205) and spaced apart thefirst support leg (209-1) to a minor axis direction (y axis) the firstlens (200), a third support leg (209-3) disposed on the fourth planesurface (206), and a fourth support leg (209-4) disposed on the fourthplane surface (206) and spaced apart the third support leg (209-3) to aminor axis direction (y axis) of the first lens (200).

Hereinafter, second, third and fourth exemplary embodiments of thepresent invention will be described in detail with reference to theaccompanying drawings. It should be readily apparent to those of skillin the art that the invention may be embodied in other particular shapeswithin the spirit and scope of the invention.

FIG. 11 is a schematic view illustrating an example where an ADP is usedas a light receiving element in a conventional Lidar module.

Referring to FIG. 11, the conventional Lidar module may comprise avoltage part (1110), a current limitation resistor (1120), a capacitor(1130), a light receiving element (APD, 1140), a readout circuit (1150),a light emitting part (1160, 1170) and a TDC (Time to Digital Converter,1180).

First, the light emitting part (1160, 1170) may comprise a light source(1170) outputting a light. Here, the light source (1170) may be a laserdiode and the laser diode (LD) may output a laser beam.

Meantime, although the light source (1170, 1470, 1570, 1670) in FIGS. 11to 19 is illustrated as one laser diode (LD), the light source (1170,1470, 1570, 1670) is illustrated as one laser diode (LD) for theconvenience of explanation related to the present invention, and itshould be noted that a plurality of light sources (laser diodes) may becomprised in the light-emitting device according to the presentinvention, the idea of which is not ruled out.

Furthermore, the voltage part (1110) may be an element for applying (orproviding) a bias voltage (1111) to a light receiving element (1140),where the size of voltage applied to the light receiving element (1140)may be determined by a current limitation resistor (1120) and thecapacitor (1130).

Likewise, although the light receiving element (1140, 1440, 1540, 1640)is also illustrated as one avalanche photo diode (APD) in FIGS. 11 to19, the light receiving element (1140, 1440, 1540, 1640) is illustratedas one APD for the convenience of explanation of the present invention,and it should be noted that the light-receiving device may be comprisedwith a plurality of light receiving elements according to the presentinvention, the idea of which is not ruled out.

The readout circuit (1150) may transmit a signal corresponding to alight detected by the light receiving element (1140) to the TDC (1180),and a Tx terminal (1160) comprised in the light emitting part (1160,1170) may also transmit a reference signal corresponding to a lightoutputted by the light source (1170) to the TDC (1180).

Particularly, the bias voltage of voltage part (1110) and gains of lightreceiving elements (APD, 1140) may maintain a predeterminedrelationship, the details of which will be continuously explained usingFIG. 12.

FIG. 12 is a schematic view illustrating an example where a gain ischanged in response to changes in temperature of a conventional Lidarmodule of FIG. 11 or to a bias voltage.

A relationship can be ascertained from FIG. 12 between a bias voltage (Xaxis) applied to the light receiving element (to be more specific, theAPD) and a gain (Y axis) of APD in a light of a particular wavelength(λ=800 nm). In addition, changes in the relationship between a relevantbias voltage (X axis) and a gain (Y axis) depending on ambienttemperature can be also ascertained.

Referring to FIG. 12, it can be noted that a bias voltage applied to theAPD must be increased from about 210V to about 245V in order to obtain asame gain (e.g., 100) when a gain axis (Y axis) is fixed at 100, and atemperature is increased (A to B) from −20° Celsius to 40° Celsius.

Meantime, based on an APD temperature condition is 0° Celsius and a biasvoltage is 200V, and in order to obtain a gain corresponding to a rangeof 10 to 100, it can be noted that, based on a 200V bias voltage appliedto the APD, about 180V˜220V bias voltage corresponding to about 20V inAPD fluctuation width must be applied to the APD.

That is, in order to adjust (or control) a gain of APD under apredetermined temperature condition and in a light of particularwavelength, it can be noted that a change in bias voltage is required.As a result, the second exemplary embodiment proposes a light-receivingdevice in which a gain of APD is changed according to the change in thebias voltage and a dynamic range can be controlled as a result thereof.

FIG. 13 is a schematic view illustrating an example where a gain of anAPD is increased in response to changes in bias voltage when atemperature is constant in a light-receiving device for increasing adynamic range according to a second exemplary embodiment of presentinvention.

Referring to FIG. 13, it can be ascertained from FIG. 13 that under aconstant temperature condition (25° Celsius), the relationship among abias voltage (X axis) applied to the light receiving element (to be morespecific, APD), a gain of APD (Y axis at left side) and a cut-offfrequency (Y axis at right side).

In more detail, in order to obtain a gain in which a gain of APD isincreased (from C to D) from about 20 to about 80, it can be noted thata bias voltage applied to the APD is increased from about 120V (310) toabout 155V (320).

Because, in the bias voltage thus increased, a frequency of lightmeasured in response to the APD is also increased, and the increasedfrequency is a frequency smaller that a cut-off frequency, the APDcomprised in the light-receiving device in response to the increasedbias voltage may be used for measurement of small quantity of light andfor measurement of large quantity of light as well according to thesecond exemplary embodiment.

All in all, the second exemplary embodiment can be used to prevent thegeneration of dead zone immeasurable by the conventional Lidar moduleand as a result, the dynamic range can be increased.

FIG. 14 is a schematic view illustrating an optical device according toa second exemplary embodiment of present invention.

Referring to FIG. 14, a Lidar module comprising an optical deviceaccording to the present invention may comprise a voltage part (1410), acurrent limitation resistor (1420), a capacitor (1430), a lightreceiving element (APD, 1440), a readout circuit (1450), a lightemitting part (1460, 1470) and a controller (Main B/D, 1480).

However, the optical device and Lidar module explained through FIGS. 4to 6, in introducing a particular function according to the presentinvention, are illustrated only with the essential elements, andtherefore it should be readily apparent to those of skill in the artthat various other elements may be comprised in the optical device andthe Lidar module.

The current limitation resistor (1420), the capacitor (1430), the lightreceiving element (APD, 1440), the readout circuit (1450), and the lightemitting part (1460, 1470) illustrated in FIG. 14 are substantially sameas those already explained in FIG. 11, such that any redundantexplanation thereto will be omitted, and the voltage part (1410) and thecontroller (1480) will be explained which are the characteristicelements of optical device according to the present invention.

The voltage part (1410) may be an element for providing (or applying) avoltage necessary for operation of the light receiving element (1440)detecting a light that is transmitted by being reflected from a subject,and may output (1411) a first bias voltage or a second bias voltage.

Here, the second bias voltage may be a voltage in which a sub voltage isadded to the first bias voltage. Furthermore, the first bias voltage maybe a DC voltage between about 10V to 300V, and may be changed in valuedepending on temperature, as explained in FIG. 12.

In more detailed explanation thereto, the first bias voltage may be a130V which is a bias voltage at C point explained through FIG. 13, andthe second bias voltage may a 155V, which is a bias voltage at D pointof FIG. 3. In this case, the sub bias voltage may be about 35V.

Meantime, the bias voltage illustrated in FIG. 13 illustrates an examplein which the second bias voltage is increased through the sub biasvoltage, through which the exemplary embodiment of FIG. 14 can beexplained, but conversely, when the sub bias voltage is a negative (−)voltage, it should be apparent that the second bias voltage may besmaller than the first bias voltage, and the light-receiving deviceaccording to the present invention does not rule out this example.

The controller (1480) may be an element for controlling an operation ofthe voltage part (1410). To be more specific, the controller (1480) maycontrol the voltage part (1410) so that the second bias voltage in thefirst bias voltage provided from the voltage part (1410) and the secondbias voltage is synchronized with an optical output of the lightemitting part (1460, 1470) to be provided (1441) to the light receivingelement (1440).

Toward this end, the controller (1480) may simultaneously input a seedsignal (1481, 1482) to the Tx terminal (1460) comprised in the lightemitting part (1460, 1470) and to the voltage part (1410), and as aresult, the voltage part (1410) may output (1441) the second biasvoltage based on a time when a relevant seed signal (1481) is inputted.

All in all, the light-receiving device of the present invention inresponse to the operation of the controller (1480) may selectivelyincrease (or control) a gain of the light receiving element (1440) onlyin a case when a light is outputted from the light source (1470)comprised in the light-emitting device (1460, 1470).

That is, a dynamic range can be effectively increased (or controlled) ina Lidar module using the APD as a light receiving element according tothe present invention.

Meantime, the sub bias voltage may be changed in response to thecharacteristics of APD used as a light receiving element, but it ispreferable that the sub bias voltage be comprised in a range of maximum+50V to −50V, and may comprise an AC or pulse type voltage that changesrelative to a time.

Furthermore, when the sub bias voltage is an AC or pulse type voltage, amedian value of sub bias voltage may be positioned between about −50V toabout 100V, and the type thereof may be changed to a linear shape or astair shape.

FIGS. 15 to 17 are schematic views illustrating a sub bias voltageapplied to a light receiving element in the optical device of FIG. 14and a second bias voltage thereof.

Referring to FIGS. 15, 16 and 17, Y axis in the graph denotes a voltage,and X axis denotes a time. Moreover, G(V) denotes an example of sub biasvoltage, and G(V)+F(V) denotes an example of second bias voltage.

To be more specific, FIGS. 15 to 17 may illustrate a second bias voltage{G(V)+F(V)} added by a sub bias voltage corresponding to G(V) when thefirst bias voltage {F(V)} is 100V.

FIG. 18 is a schematic view illustrating a Lidar module according to athird exemplary embodiment of present invention.

Referring to FIG. 18, the Lidar module according to the presentinvention may comprise a first voltage part (1510), a current limitationresistor (1520), a capacitor (1530), a light receiving element (APD,1540), a readout circuit (1550), a light emitting part (1560, 1570), acontroller (Main B/D, 1580) and a second voltage part (1590).

The current limitation resistor (1520), the capacitor (1530), the lightreceiving element (APD, 1540), the readout circuit (1550), and the lightemitting part (1560, 1570) illustrated in FIG. 18 are substantially sameas those already explained in FIGS. 11 and 14, such that any redundantexplanation thereto will be omitted, and the first voltage part (1510),the controller (1580) and the second voltage part (1590) will beexplained which are the characteristic elements.

The first voltage part (1510) and the second voltage part (1590) may berespectively an element for providing (or applying) a voltage necessaryfor operation of the light receiving element (1540) detecting a lightthat is transmitted by being reflected from a subject.

To be more specific, the first voltage part (1510) may provide a biasvoltage (1511) to the light receiving element and the second voltagepart (1590) may provide a sub bias voltage (1591) to the light receivingelement.

Here, the voltage applied to the light receiving element (APD, 1540) maybe a voltage in which the bias voltage (1511) provided by the firstvoltage part (1510) is added by the sub bias voltage (1591) provided bythe second voltage part (1590). Furthermore, the bias voltage (1511)provided from the first voltage part (1510) may be a DC voltage betweenabout 10V to 300V, and may be changed in value depending on temperature,as explained in FIG. 12.

In more detailed explanation thereto, the bias voltage provided from thefirst voltage part (1510) may be a 120V which is a bias voltage at Cpoint explained through the abovementioned FIG. 13, and the bias voltagemay about 35V, which is a difference (subtraction) between 155V which isa bias voltage at D point of FIG. 13 and 120V which is a bias voltage atC point.

That is, one end of the light receiving element (APD, 1540) at D pointmay be applied with about 155V in which, a 120V which is a bias voltage(1511) provided from the first voltage part (1510) is added by 35V whichis the sub bias voltage (1591). As a result, the light receiving element(APD, 1540) may operate while having about a 80-gain at a cut-offfrequency of about 800 Mhz.

The controller (1580) may be an element for controlling an operation ofthe second voltage part (1590). To be more specific, the controller(1580) may control the second voltage part (1590) so that the biasvoltage (1591) provided by the second voltage part (1590) issynchronized with an optical output of the light emitting part (1560,1570) to be provided to the light receiving element (1540).

Toward this end, the controller (1580) may simultaneously input a seedsignal (1581, 1582) to a Tx terminal (1560) comprised in the lightemitting part (1560, 1570) and to the second voltage part (1590), and asa result, the second voltage part (1590) may output the sub bias voltagebased on a time when a relevant seed signal (1581) is inputted.

All in all, the Lidar module of the present invention in response to theoperation of the controller (1580) may selectively increase (or control)a gain of the light receiving element (1540) only in a case when a lightis outputted from the light source (1570) comprised in thelight-emitting device (1560, 1570).

FIG. 19 is a schematic view illustrating a Lidar module according to afourth exemplary embodiment of present invention.

Referring to FIG. 19, the Lidar module according to the presentinvention may comprise a first voltage part (1610), a current limitationresistor (1620), a capacitor (1630), a light receiving element (APD,1640), a readout circuit (1650), a light emitting part (1660, 1670), acontroller (Main B/D, 1680), a second voltage part (1690) and amonitoring photo diode (MPD, 1700).

The current limitation resistor (1620), the capacitor (1630), the lightreceiving element (APD, 1640), the readout circuit (1650), and the lightemitting part (1660, 1670) illustrated in FIG. 19 are substantially sameas those already explained in FIGS. 11 and 18, such that any redundantexplanation thereto will be omitted, and the first voltage part (1610),the second voltage part (1690) and the monitoring photo diode (MPD,1700) will be explained.

The first voltage part (1610) and the second voltage part (1690) may berespectively an element for providing (or applying) a voltage necessaryfor operation of the light receiving element (1640) detecting a lightthat is transmitted by being reflected from a subject.

To be more specific, the first voltage part (1610) may provide a biasvoltage (1611) to the light receiving element and the second voltagepart (1690) may provide a sub bias voltage (1691) to the light receivingelement.

Here, the voltage applied to the light receiving element (APD, 1640) maybe a voltage in which the bias voltage (1611) provided by the firstvoltage part (1610) is added by the sub bias voltage (1691) provided bythe second voltage part (1690). Furthermore, the bias voltage (1611)provided from the first voltage part (1610) may be a DC voltage betweenabout 10V to about 300V, and may be changed in value depending ontemperature, as explained in FIG. 12.

In more detailed explanation thereto, the bias voltage (1611) providedfrom the first voltage part (1610) may be a 120V which is a bias voltageat C point explained through the abovementioned FIG. 13, and the subbias voltage (1691) supplied from the second voltage part (1690) mayabout 35V, which is a difference (subtraction) between 155V which is abias voltage at D point of FIG. 13 and 120V which is a bias voltage at Cpoint.

That is, one end of the light receiving element (APD, 1640) at D pointmay be applied with about 155V in which, a 120V which is a bias voltage(1611) provided from the first voltage part (1610) is added by 35V whichis the sub bias voltage (1691). As a result, the light receiving element(APD, 1640) may operate while having about a 80-gain at a cut-offfrequency of about 800 Mhz.

Furthermore, the monitoring photo diode (MPD, 1700) is an element forcontrolling an operation of the second voltage part (1690). To be morespecific, the MPD (1700) may detect (1701) an optical output outputtedfrom the light emitting part (1660, 1670), and control (1702) the secondvoltage part (1690) so that the sub bias voltage (1691) provided by thesecond voltage part (1690) is synchronized with an optical output of thelight emitting part (1660, 1670) to be provided to the light receivingelement (1640).

Toward this end, the MPD (1700) may input a seed signal (1702) to thesecond voltage part (1690) in response to a part of detected opticaloutput (1701) in the optical outputs outputted from the light emittingpart (1660, 1670), and as a result, the second voltage part (1690) mayoutput the sub bias voltage (1691) based on a time when a relevant seedsignal (1702) is inputted.

All in all, the Lidar module of the present invention in response to theoperation of the MPD (1700) may selectively increase (or control) a gainof the light receiving element (1640) only in a case when a light isoutputted from a light source (1670) comprised in the light-emittingdevice (1660, 1670).

That is, according to the third and fourth exemplary embodimentsillustrated in FIGS. 18 and 19, a dynamic range can be effectivelyincreased (or controlled) in a Lidar module using the APD as a lightreceiving element.

Meanwhile, although the sub bias voltage may be changed in response tothe characteristics of the used APD, it is preferable that the sub biasvoltage be comprised within a maximum range of +50V to −50V, and maycomprise an AC or pulse type voltage that changes to a time.

Furthermore, when the sub bias voltage is an AC or pulse type voltage, amedian value of sub bias voltage may be positioned between about −50V toabout 100V, and the type thereof may be changed to a linear shape or astair shape, the explanation of which has been already elaboratedthrough FIG. 14.

All in all, the light-receiving device for increasing the dynamic rangeaccording to the second, third and fourth exemplary embodiments canincrease the dynamic range by changing a gain of light receivingelement, and when an APD is used as a light receiving element, a deadzone problem that fails to react to a relatively large quantity of lightcan be solved.

The hitherto detailed explanations should not be limitedly construed inall respects and should be considered as exemplary. The scope of presentinvention should be determined by a rational interpretation of attachedclaims, and all changes within the equivalent scope of the presentinvention should be comprised in the scope of the present invention.

What is claimed is:
 1. A light-receiving device, comprising: a firstlens comprising a first lens surface for receiving a light from anoutside and a second lens surface for changing a path of the lightreceived by the first lens surface and outputting the light to theoutside; and a sensor on which light transmitted through the second lenssurface is incident, wherein the first lens surface is a sphericalsurface, the second lens surface is an aspherical surface having anaspheric shape, and a focus of the first lens surface deviates from asensor surface of the sensor.
 2. The light-receiving device of claim 1,wherein the focus of the first lens surface deviates from the sensorsurface of the sensor to an optic axis direction.
 3. The light-receivingdevice of claim 1, wherein a distance from a principal point of thefirst lens to the sensor surface of the sensor is shorter or longer thana focal distance.
 4. A light-receiving device, comprising: a first lenscomprising a first lens surface for receiving a light from an outsideand a second lens surface for changing a path of the light received bythe first lens surface and outputting the light to the outside; and asensor on which light transmitted through the second lens surface isincident, wherein the first lens surface is a spherical surface, thesecond lens surface is an aspherical surface, and a focus of the firstlens surface deviates from a sensor surface of the sensor, and whereinthe first lens surface comprises a first spherical surface, and thesecond lens surface comprises a first aspherical surface, a secondaspherical surface and a third aspherical surface.
 5. Thelight-receiving device of claim 4, wherein the first aspherical surfaceis disposed on a distal end of one side to a minor axis direction of thefirst lens, the third aspherical surface is disposed on a distal end ofother side to the minor axis direction of the first lens, and the secondaspherical surface is interposed between the first aspherical surfaceand the third aspherical surface.
 6. The light-receiving device of claim4, wherein a first inflection point exists between the first asphericalsurface and the second aspherical surface on a cross-section to a minoraxis direction of the first lens, and wherein a second inflection pointexists between the third aspherical surface and the second asphericalsurface on a cross-section to the minor axis direction of the firstlens.
 7. The light-receiving device of claim 4, wherein the firstspherical surface, the first aspherical surface, the second asphericalsurface and the third aspherical surface are formed with a convexcurvature to a direction opposite to a direction disposed with thesensor on a cross-section to a major axis direction of the first lens.8. The light-receiving device of claim 4, wherein the second asphericalsurface is formed with a convex curvature to a direction disposed withthe sensor on a cross-section to a minor axis direction of the firstlens.
 9. The light-receiving device of claim 4, wherein the first lenscomprises: a first plane surface disposed between a distal end of oneside to a minor axis direction of the first lens on the first sphericalsurface and a distal end of one side to the minor axis direction of thefirst lens on the first aspherical surface; and a second plane surfacedisposed between a distal end of the other side to the minor axisdirection of the first lens on the first spherical surface and a distalend of the other side to the minor axis direction of the first lens onthe third aspherical surface, and wherein the first plane surface andthe second plane surface are perpendicular to the minor axis of thefirst lens.
 10. The light-receiving device of claim 9, wherein the firstplane surface and the second plane surface is a surface generated whenthe first lens is manufactured by molding.
 11. The light-receivingdevice of claim 4, wherein the first lens comprises: a third planesurface disposed between a distal end of one side to a major axisdirection of the first lens on the first spherical surface and a distalend of one side to a major axis direction of the first lens on the firstaspherical surface, the second aspherical surface and the thirdaspherical surface; and a fourth plane surface disposed between a distalend of the other side to a major axis direction of the first lens on thefirst spherical surface and a distal end of the other side to the majoraxis direction of the first lens on the first aspherical surface, thesecond aspherical surface and a third aspherical surface, wherein thethird plane surface and the fourth plane are perpendicular to an opticalaxis of the first lens.
 12. The light-receiving device of claim 11,wherein the first lens comprises a plurality of support legs, andwherein the plurality of support legs comprises a first support legdisposed on the third plane surface, a second support leg disposed onthe third plane surface and spaced apart the first support leg to theminor axis direction of the first lens, a third support leg disposed onthe fourth plane surface, and a fourth support leg disposed on thefourth plane surface and spaced apart the third support leg to the minoraxis direction of the first lens.
 13. The light-receiving device ofclaim 11, wherein the first lens comprises a fifth plane surfacedisposed between the first spherical surface and the third planesurface, and a sixth plane surface disposed between the first sphericalsurface and the fourth plane surface, wherein the fifth plane surfaceand the sixth plane surface is disposed to be symmetrical about an opticaxis.
 14. The light-receiving device of claim 12, wherein the fifthplane surface and the sixth plane surface is respectively a cut surfacegenerated when a plurality of first lenses is cut during manufacturingof the plurality of first lens using a molding.
 15. The light-receivingdevice of claim 4, wherein the first spherical surface has a positive(+) refractive power on a cross-section to a major axis direction of thefirst lens, the first aspherical surface, the second aspherical surfaceand the third aspherical surface have a negative (−) refractive power ona cross-section to the major axis direction of the first lens.
 16. Thelight-receiving device of claim 4, wherein the first spherical surfaceand the second aspherical surface have a positive (+) refractive poweron a cross-section to a minor axis direction of the first lens, and thefirst aspherical surface and the third aspherical surface have anegative (−) refractive power on a cross-section to the minor axisdirection of the first lens.
 17. A light-receiving device, comprising: afirst lens comprising a first lens surface for receiving light from anoutside and a second lens surface for changing a path of the lightreceived by the first lens surface and outputting the light to theoutside; and a sensor on which light transmitted through the second lenssurface is incident, wherein the first lens surface comprises aspherical surface, the second lens surface comprises a first asphericalsurface, a second aspherical surface and a third aspherical surface,wherein the first aspherical surface is disposed on a distal end of oneside to a minor axis direction of the first lens, the third asphericalsurface is disposed on a distal end of other side to the minor axisdirection of the first lens, and the second aspherical surface isdisposed between the first aspherical surface and the third asphericalsurface, wherein the first spherical surface has a positive (+)refractive power on a cross-section to a major axis direction of thefirst lens, the first aspherical surface, the second aspherical surfaceand the third aspherical surface have a negative (−) refractive power ona cross-section to the major axis direction of the first lens, whereinthe first spherical surface and the second aspherical surface have apositive (+) refractive power on a cross-section to the minor axisdirection of the first lens, and the first aspherical surface and thethird aspherical surface have a negative (−) refractive power on across-section to the minor axis direction of the first lens, and whereina focus of the first lens deviates from the sensor surface of thesensor.
 18. The light-receiving device of claim 17, wherein the focus ofthe first lens surface deviates from the sensor surface of the sensor toan optic axis direction.
 19. The light-receiving device of claim 17,wherein a distance from a principal point of the first lens to thesensor surface of the sensor is shorter or longer than a focal distance.20. A lidar, comprising: a light-emitting device for emitting light; anda light-receiving device for receiving the light emitted from thelight-emitting device, wherein the light-receiving device comprises: afirst lens comprising a first lens surface for receiving light from anoutside and a second lens surface for changing a path of the lightreceived by the first lens surface and outputting the light to theoutside; and a sensor on which light transmitted through the second lenssurface is incident and wherein the first lens surface is a sphericalsurface, the second lens surface is an aspherical surface having anaspheric shape, and a focus of the first lens deviates from a sensorsurface of the sensor.
 21. The lidar of claim 20, wherein the first lenssurface comprises a first spherical surface, and wherein the second lenssurface comprises a first aspherical surface, a second asphericalsurface and a third aspherical surface.